As wireless communication systems such as cellular telephones, satellite and microwave communication systems become widely deployed and continue to attract a growing number of users, there is a pressing need to accommodate a large and variable number of communication subsystems transmitting a growing volume of data with a fixed resource such as a fixed channel bandwidth accommodating a fixed data packet size. Traditional communication system designs employing a fixed resource (e.g., a fixed data rate for each user) have become challenged to provide high, but flexible, data transmission rates in view of the rapidly growing customer base. Various standards and interoperability requirements are developed on an ongoing basis for present and future communications networks. The use of standards ensures that equipment available in the marketplace operates correctly with equipment from a variety of manufacturers and service providers, and in a variety of locales so that to a user carrying the equipment from place to place and even from country to country, the use of the equipment remains convenient and the details of the operations of the network are virtually transparent to the user.
For example, the third Generation Partnership Project Long Term Evolution (“3GPP LTE”) is the name generally used to describe an ongoing effort across the industry to improve the Universal Mobile Telecommunications System (“UMTS”) for mobile communications. The improvements are being made to cope with continuing new requirements and the growing base of users. Goals of this broad-based project include improving communication efficiency, lowering costs, improving services, making use of new spectrum opportunities, and achieving better integration with other open standards, and backwards compatibility with some existing infrastructure that is compliant with earlier standards. The project envisions a packet-switched communications environment with support for such services as Voice over Internet Protocol (“VoIP”) and Multipedia Broadcast Multicast Service (“MBMS”). MBMS may support services where base stations transmit to multiple user equipment simultaneously, such as mobile televisions or radio broadcasts, for example. The 3GPP LTE project is not itself a standard-generating effort, but will result in new recommendations for standards for the UMTS.
The UMTS Terrestrial Radio Access Network (“UTRAN”) includes multiple Radio Network Subsystems (“RNS”); each of which may contain at least one Radio Network Controller (“RNC”). However, it should be noted that the RNC may not be present in the actual implemented systems incorporating Long Term Evolution (“LTE”) or extended UTRAN (“e-UTRAN”). LTE may include a centralized or decentralized entity for control information. In UTRAN operation, each RNC may be connected to multiple Node Bs, which are the UMTS' counterpart to Global System for Mobile Communications (“GSM”) base stations. In E-UTRAN systems, the eNode B may be, or is, connected directly to the access gateway (“aGW,” sometimes referred to as the services gateway “sGW”). Each Node B may be in radio contact with multiple user equipment (“UE”) (generally, user equipment includes mobile transceivers or cellular phones, although other devices such as fixed cellular phones, mobile web browsers, laptops, PDAs, MP3 players, and gaming devices with transceivers may also be UE) via the radio Uu interface. In this document, the abbreviation for user equipment (“UE”) will be synonymous with the abbreviation for mobile station (“MS”), and MS will be used primarily. Mobile stations may also be cellular phones, PDAs, MP3 players, mobile web browsers, mobile PCs and the like.
The wireless communication systems as described herein are applicable to, as non limiting examples, existing and future wireless systems, such as GSM, 3G, 3.5G, 4G etc., extended GSM, IMT-A, or future wireless communications systems.
Messages in these modern communications systems are packets formed in frames, blocks and bursts. The bursts may contain interrelated data bits that have been intentionally reordered by a process called “interleaving”. This reordering of bits means that no single burst of, for example, a four burst paging message, has a complete set of consecutive message bits within it. Instead, the consecutive bits have been spread out over several bursts. To receive the entire message, a receiver has to collect all four bursts and “deinterleave”—reorder—the received bits in a predetermined way. The interleaving is part of the transmission scheme and aids error detection and error correction using forward error correction (FEC) and cyclic redundancy check (CRC). In this manner even a partially garbled transmission may often be correctly received, or at least, the error detected at the receiver so that a re-transmission may be requested. For example, if one of the bursts is received incorrectly, enough information from the original data string may remain in the other received bursts to perform error detection and correction, and decode the message correctly. This can often occur without the need for retransmission.
As a method of improving battery and power performance in such systems, approaches to reduce power consumption in certain modes have been proposed. Generally, the approach is to maintain the mobile station (hereinafter “MS”) in a low power or “sleep” state as much as possible when in the idle mode. In the “sleep” state, the power used, especially to the radio functions of the device, is limited to the minimum needed for proper operation, and importantly few RF circuits are powered.
The receiver in the MS still expends much of its idle mode battery power receiving the broadcast or paging messages. Periodically, the MS leaves sleep mode and enters an active idle mode where the device monitors, for example, the paging channel (PCH) and broadcast (BCCH) channels.
A continuing need exists for an improved and commercially practical message decoding method and apparatus to provide a robust identification of empty paging messages, or other repetitive messages, to enable the MS receiver to return to sleep mode quickly and thereby conserve power.